Bottom Seams, Keel, Bow-Sprit (Day 48, 49 & 50)

Managed 2.5 days of work on the boat in a 3 day weekend. Inner & Outer Chine seams welds are done, the outer chine just needs the side face to be sanded flush and all the seams need to be tested for leaks with compressed air. I also fitted the keel on and tested it for leaks, there were a few very small pin holes which in reality may never fill with sea water but I was running about 2 bar of pressure through the keel so no holes would be missed, the last thing I want is the keel filling up with water and not being able to get to it. The underside of the bow-sprit is also finished and I started to weld the undersides of the fenders until I ran out of argon gas - Time to pack up and call it a day :-)

The weld joints that will be sanded flush to one side i.e. external corners were prepared with the plates offset or back gouged so there would be full penetration through the corner. I did a sample and tested it to destruction which you can see in the coming photos.

Full penetration - This is ideal although achieving this 100% of the time is difficult. If you don't get full peno, you need to make sure your back-gouging is deep enough.

$6 a pop for each disk at Bunnings, $1.20 each on Ebay!

Back-gouging inner & outer chines

Inner chine MIG welds

TIG weld to bridge gap between the MIG welds

Keel being fitted

Test sample for breaking

Prep'd outside corner per welds on boat, this corner is welded & sanded on one side.

Can't bend it by hand, something more is needed....

Big block of wood & a concrete floor to the rescue

10 whacks later with the big block of wood

It took about 20 blows with the block of wood to bend the test sample this far, 90 deg.

Only one crack in the metal on the sanded side, internal fillet is unaffected, crack is above the weld, looks like it's in the heat affected zone (HAZ) top left hand corner. Considering the coupon was pummeled with a 5" x 5" timber post on a concrete floor repeatedly, this is an OK result.

I'm pretty happy with this, the boat would need to be completely twisted for the welds to start to crack.

Capping off the transom - keel.


Capped of front part of keel

Finished the underside work required for the bow sprit

Tapping 1/4 thread for the fuel line connections

Tapping a thread for the compressed air Nitto fittings - Problem, should have done the hole further up, not enough depth here for the tap to work.

Spray warm soapy water onto the joint,  this is what leaks look like :-( I have a few to fix next weekend

Compressed air blowing into the keel

Another view of the bow sprit underside


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